JPWO2018180637A1 - Rotor, motor, electric power steering device - Google Patents

Abstract

A shaft that rotates about a central axis extending along the up-down direction, a rotor core fixed to the shaft, and a plurality of first cores provided at a part of the rotor core in the axial direction and arranged at intervals in the circumferential direction A first magnet and a second magnet provided at a position different from the first magnet in the axial direction of the rotor core and arranged at intervals in the circumferential direction; A rotor having the same magnetic flux density but different shapes.

Description

  The present invention relates to a rotor, a motor, and an electric power steering device.

  The rotor of the motor includes a rotor core that rotates together with the shaft, and a plurality of magnets provided in a circumferential direction of the rotor core. The cogging torque generated during the operation of the motor leads to an increase in vibration and noise of the motor. For this reason, it is desired to suppress the occurrence of cogging torque in the motor.

  For example, Patent Document 1 discloses a configuration in which a rotor core is divided into a plurality in the axial direction, and magnets of the plurality of rotor cores are inclined (skewed) with respect to the axial direction. Further, in this Patent Document 1, magnets are provided in a plurality of stages in the axial direction of the rotor core, and a magnetic flux, a circumferential width dimension, and an axial length dimension between one stage magnet and another stage magnet are provided. A configuration in which the thickness and the area in the radial direction are different from each other is disclosed.

JP 2014-12265 A

  However, such a motor has a problem that it takes time to assemble the rotor and the productivity is reduced.

  In view of the above circumstances, an object of the present invention is to provide a rotor, a motor, and an electric power steering device capable of suppressing cogging torque and simplifying assembly.

  One aspect of the rotor of the present invention is a shaft that rotates around a central axis extending along the up-down direction, a rotor core fixed to the shaft, and a part provided in the axial direction of the rotor core, and is provided in a circumferential direction. A plurality of first magnets arranged at intervals, and a plurality of second magnets provided at positions different from the first magnets in the axial direction of the rotor core and arranged at intervals in the circumferential direction Wherein the first magnet and the second magnet have the same magnetic flux density and different shapes.

  One embodiment of a motor according to the present invention includes the rotor described above, and a stator that faces the rotor via a gap in a radial direction.

  One embodiment of the electric power steering apparatus of the present invention includes the above-described motor.

  According to one aspect of the present invention, there is provided a rotor, a motor, and an electric power steering device capable of suppressing cogging torque and simplifying assembly.

FIG. 1 is a schematic sectional view of a motor according to one embodiment. FIG. 2 is a cross-sectional view of the motor according to the embodiment, taken along line II-II in FIG. FIG. 3 is a cross-sectional view of the motor of one embodiment, taken along line III-III in FIG. FIG. 4 is a perspective view showing a part of the rotor according to the embodiment. FIG. 5 is a diagram illustrating a part of the motor according to the embodiment, and is an enlarged sectional view of FIG. 2. FIG. 6 is a diagram illustrating a part of the motor according to the embodiment, and is an enlarged cross-sectional view of FIG. 3. FIG. 7 is a perspective view showing a part of the stator according to the embodiment. FIG. 8 is a diagram illustrating a waveform of a cogging torque in the motor according to the embodiment. FIG. 9 is a schematic diagram of an electric power steering device including a motor according to one embodiment. FIG. 10 is a perspective view showing a modification of the stator of the embodiment. FIG. 11 is a perspective view showing a modified example of the rotor of the embodiment.

FIG. 1 is a schematic sectional view of a motor 10 according to the present embodiment.
As shown in FIG. 1, the motor 10 includes a rotor 20 and a stator 30.

In the following description, a direction parallel to the central axis J is simply referred to as “axial direction” or “vertical direction”, a radial direction about the central axis J is simply referred to as “radial direction”, and the central axis J , That is, around the axis of the central axis J is simply referred to as “circumferential direction”. Further, in the following description, “plan view” means a state viewed from the axial direction. In this specification, the upper side in FIG. 1 in the axial direction along the central axis J is simply called “upper side”, and the lower side is simply called “lower side”. Note that the vertical direction does not indicate the positional relationship or direction when the device is incorporated in an actual device.
Further, in the following drawings, in order to make each configuration easy to understand, the scale and the number of the actual structure may be different from those of the actual structure.

[Rotor]
The rotor 20 includes a shaft 21 disposed along a central axis J extending in the up-down direction, a rotor core 22 fixed to the shaft 21, a first magnet 23, and a second magnet 24.

  The shaft 21 is supported by a plurality of bearings 15 and 16 provided on the motor housing 11 so as to be rotatable around a central axis J. The shaft 21 has a columnar shape extending in a direction along the central axis J. The shaft 21 is fixed to the rotor core 22 by press fitting or bonding. Further, the shaft 21 may be fixed to the rotor core 22 via a resin member or the like. That is, the shaft 21 is directly or indirectly fixed to the rotor core 22. Note that the shaft 21 may be a hollow member, and is not particularly limited.

  FIG. 2 is a cross-sectional view of the motor 10 of the present embodiment taken along line II-II in FIG. FIG. 3 is a cross-sectional view of the motor of this embodiment, taken along line III-III in FIG. FIG. 4 is a perspective view showing a part of the rotor of the present embodiment. FIG. 5 is a diagram showing a part of the motor of the present embodiment, and is an enlarged sectional view of FIG. FIG. 6 is a view showing a part of the motor of the present embodiment, and is an enlarged sectional view of FIG.

  As shown in FIGS. 2 and 3, the rotor core 22 is a cylindrical member. The outer shape of the rotor core 22 is polygonal when viewed from the axial direction. In the present embodiment, the outer shape of the rotor core 22 is an octagon. In other words, the rotor core 22 is a hollow substantially octagonal column. Note that the outer shape of the rotor core 22 may be circular or the like. The rotor core 22 is a laminated steel sheet in which a plurality of electromagnetic steel sheets are laminated in the axial direction. The rotor core 22 is provided with a through hole 22h at the center in plan view, through which the shaft 21 passes.

  As shown in FIG. 4, the first magnet 23 is provided on a part of the upper part of the rotor core 22 in the axial direction. The first magnet 23 is a plate-like member extending in the axial direction.

  As shown in FIG. 2, the first magnets 23 are arranged at equal intervals in the circumferential direction. When viewed from the axial direction, the first magnet 23 has a pair of first side surfaces 23s facing in the circumferential direction, a first outer surface portion (outer peripheral surface) 23t facing in the radial direction, and a first magnet 23 facing inward in the radial direction. 1 inner surface part 23u.

  The pair of first side surfaces 23s extend radially outward from both circumferential ends of the first inner surface 23u. The first side surface portion 23s is substantially straight when viewed from the axial direction.

  The first inner surface 23u is substantially straight when viewed from the axial direction. The first inner surface portion 23u radially opposes a core outer peripheral surface 22f facing radially outward of the rotor core 22.

  End portions on both circumferential sides of the first outer surface portion 23t are connected to the pair of first side surface portions 23s. In the present embodiment, the first outer surface portion 23t is a curved surface that protrudes radially outward, and has an arc shape centered on the central axis J. Note that the first outer surface portion 23t does not necessarily need to be a curved surface. The first outer surface portion 23t may be a flat surface. That is, when viewed from the axial direction, the outer shape of the first outer surface portion 23t may be linear.

  As shown in FIG. 4, the second magnet 24 is provided at a position different from the first magnet 23 in the axial direction of the rotor core 22. Specifically, the second magnet 24 is provided on a part of the rotor core 22 on the lower side in the axial direction. The second magnet 24 is arranged to be in contact with the lower end of the first magnet 23. In the axial direction, a gap may be provided between the first magnet 23 and the second magnet 24, and an adhesive or another member may be interposed.

  As shown in FIG. 3, the second magnets 24 are arranged at regular intervals in the circumferential direction. The second magnet 24 is a plate-shaped member extending in the axial direction. When viewed from the axial direction, the second magnet 24 includes a pair of second side surfaces 24s facing in the circumferential direction, a second outer surface portion (outer peripheral surface) 24t facing radially outward, and a second magnet 24 facing radially inward. 2 inner surface part 24u.

  The pair of second side surfaces 24s extend radially outward from both circumferential ends of the second inner surface 24u. The second side surface portion 24s is substantially linear when viewed from the axial direction.

  The second inner surface portion 24u is substantially straight when viewed from the axial direction. The second inner surface portion 24u is radially opposed to the core outer peripheral surface 22f that faces outward in the radial direction of the rotor core 22.

  Ends on both sides in the circumferential direction of the second outer surface portion 24t are connected to the pair of second side surface portions 24s. In the present embodiment, the second outer surface portion 24t is a curved surface that protrudes radially outward and has an arc shape centered on the central axis J. The radius of curvature of the second outer surface portion 24t is equal to the radius of curvature of the first outer surface portion 23t. Note that the second outer surface portion 24t does not necessarily need to be a curved surface. The second outer surface portion 24t may be a flat surface. That is, when viewed from the axial direction, the outer shape of the second outer surface portion 24t may be linear.

The first magnet 23 and the second magnet 24 have the same magnetic flux density and different shapes.
Specifically, the first magnet 23 and the second magnet 24 have the same volume. The dimensions of the first magnet 23 and the second magnet 24 are different from each other in at least one of a circumferential direction, an axial direction, and a radial direction about the center axis J.

  As shown in FIG. 4, the first magnet 23 and the second magnet 24 have different circumferential widths W1 and W2. The circumferential width W1 of the first magnet 23 is smaller than the circumferential width W2 of the second magnet 24. When the first magnet 23 and the second magnet 24 arranged in the axial direction are viewed from the axial direction, the second magnet 24 protrudes outward in both circumferential directions from the first magnet 23.

  As shown in FIGS. 5 and 6, the thicknesses T1 and T2 of the first magnet 23 and the second magnet 24 in the radial direction about the center axis J are different from each other. In the radial direction, the thickness T1 of the thickest portion of the first magnet 23 is larger than the thickness T2 of the thickest portion of the second magnet 24.

  As shown in FIG. 4, in the present embodiment, the axial length L1 of the first magnet 23 is the same as the axial length L2 of the second magnet 24. As described above, the first magnet 23 and the second magnet 24 have the same volume. Therefore, in the present embodiment, the first magnet 23 and the second magnet 24 have the same cross-sectional area in a cross section orthogonal to the axial direction.

  Note that the axial length L1 of the first magnet 23 may be different from the axial length L2 of the second magnet 24. In this case, the first magnet 23 and the second magnet 24 have different cross-sectional areas in a cross section orthogonal to the axial direction. As an example, the axial length L2 of the second magnet 24 is greater than the axial length L1 of the first magnet 23, and the sectional area of the first magnet 23 is greater than the sectional area of the second magnet 24. Larger configurations can be employed. As another example, the axial length L1 of the first magnet 23 is greater than the axial length L2 of the second magnet 24, and the cross-sectional area of the second magnet 24 is the first magnet 23. A configuration larger than the cross-sectional area of 23 can be adopted.

The position of the center Mc1 in the circumferential direction of the first magnet 23 is the same as the position of the center Mc2 in the circumferential direction of the second magnet 24.
Note that the position of the center Mc1 in the circumferential direction of the first magnet 23 may be different from the position of the center Mc2 in the circumferential direction of the second magnet 24.

  The first magnet 23 and the second magnet 24 are made of the same type of magnetic material. The first magnet 23 and the second magnet 24 are a sintered magnet using a neodymium-based material, a bonded magnet, and a magnet using a ferrite-based material, respectively. The first magnet 23 and the second magnet 24 may be made of different types of magnetic materials.

[Stator]
FIG. 7 is a perspective view showing a part of the stator of the present embodiment.
The stator 30 has a first stator core 31, a second stator core 32, a coil 30C (see FIG. 1), and an insulating member 30Z (see FIG. 1). The first stator core 31 and the second stator core 32 are arranged side by side in the axial direction with the center axis J as the center. The surfaces of the first stator core 31 and the second stator core 32 that face each other in the axial direction are in contact with each other.

  The first stator core 31 is arranged on a part of the stator 30 on the upper side in the axial direction. The first stator core 31 is a laminated steel sheet in which a plurality of electromagnetic steel sheets are laminated in the axial direction. The first stator core 31 has an annular first core back portion 37 and a plurality of first teeth 33. In the present embodiment, the first stator core 31 is a so-called split core. The first core back portion 37 is configured by connecting a plurality of fan-shaped core pieces 39A in a circumferential direction.

Each of the core pieces 39A constituting the first core back portion 37 has a plurality of first grooves 39s that are recessed radially inward on the outer surface. Each first groove 39s is located radially outside of each first tooth 33.
The first stator core 31 may be not only a split core but also another type of core such as a so-called straight core or round core.

  The first teeth 33 are provided on the inner peripheral surface of each core piece 39A. The first teeth 33 extend radially outward from the inner side surface of the first core back portion 37. The first teeth 33 are arranged at equal intervals in the circumferential direction on the inner side surface of the first core back portion 37. The first teeth 33 face the rotor 20 in the radial direction.

The first tooth 33 has a first umbrella 35 at a radially inner end of the first tooth 33. The first umbrella 35 extends from the radially inner end of the first tooth 33 to both circumferential sides. A gap is formed between adjacent first umbrellas 35 in the circumferential direction. In the following description, the gap is referred to as a first slot open 40A.
The first umbrella 35 faces the first magnet 23 in the radial direction.

  The second stator core 32 is arranged on a part of the stator 30 on the lower side in the axial direction. The second stator core 32 is arranged in contact with the lower end of the first stator core 31 in the axial direction. The second stator core 32 is joined to the first stator core 31 by caulking or the like. The second stator core 32 is a laminated steel sheet in which a plurality of electromagnetic steel sheets are laminated in the axial direction. As shown in FIGS. 3, 6, and 7, the second stator core 32 has an annular second core back portion 38 and a plurality of second teeth 34.

In the present embodiment, the second stator core 32 is a so-called split core. The second core back portion 38 is configured by connecting a plurality of fan-shaped core pieces 39B in the circumferential direction. Each core piece 39B constituting the second core back portion 38 has a plurality of second grooves 39t that are recessed radially inward on the outer surface. Each second groove 39t is located radially outward of each second tooth 34. The circumferential position of the second groove 39t is the same as the circumferential position of the first groove 39s.
The second stator core 32 may be not only a split core but also another type of core such as a so-called straight core or round core.

  The second teeth 34 are provided on the inner peripheral surface of each core piece 39B. The second teeth 34 extend radially outward from the inner surface of the second core back portion 38. The second teeth 34 are arranged at equal intervals in the circumferential direction on the inner surface of the second core back portion 38. The second teeth 34 face the rotor 20 in the radial direction.

The second tooth 34 has a second umbrella 36 at a radially inner end of the second tooth 34. The second umbrella 36 extends from the radially inner end of the second tooth 34 to both sides in the circumferential direction. A gap is formed between adjacent second umbrellas 36 in the circumferential direction. In the following description, the gap is referred to as a second slot open 41A.
The second umbrella 36 radially opposes the second magnet 24.

  As shown in FIG. 7, the first teeth 33 and the second teeth 34 overlap in the axial direction. The center Mc11 of the width in the circumferential direction of the first tooth 33 and the center Mc12 of the width in the circumferential direction of the second tooth 34 overlap each other in the axial direction. The width W21 of the first teeth 33 in the circumferential direction is the same as the width W22 of the second teeth 34 in the circumferential direction.

  The shapes of the first umbrella 35 and the second umbrella 36 are different from each other. Specifically, the dimensions of the first umbrella 35 and the second umbrella 36 are different from each other in at least one of the circumferential direction and the axial direction. In the present embodiment, the first umbrella 35 and the second umbrella 36 have different widths W11 and W12 in the circumferential direction. The circumferential width W11 of the first umbrella 35 is larger than the circumferential width W12 of the second umbrella 36. Thus, the width of the first slot open 40A in the circumferential direction is smaller than the width of the second slot open 41A.

  The axial length L11 of the first umbrella 35 is the same as the axial length L1 of the first magnets 23 facing in the radial direction. The axial length L12 of the second umbrella 36 is the same as the axial length L2 of the radially opposed second magnets 24. In the present embodiment, the axial length L11 of the first umbrella 35 is the same as the axial length L12 of the second umbrella 36.

  In the present embodiment, the dimension of the first stator core 31 in the axial direction is the same as the dimension of the second stator core 32 in the axial direction. That is, the dimension of the first core back part 37 is the same as the dimension of the second core back part 38 in the axial direction. In the axial direction, the dimensions of the first teeth 33 are the same as the dimensions of the second teeth 34.

  The material of the insulating member 30Z (see FIG. 1) is an insulating resin. The coil 30C (see FIG. 1) is wound around the first teeth 33 and the second teeth 34 via the insulating member 30Z. The material of the insulating member 30 </ b> Z is not limited to resin as long as it has insulating properties, and other materials may be used.

FIG. 8 is a diagram illustrating a waveform of the cogging torque in the motor according to the present embodiment.
In the motor 10 of the present embodiment, the rotor 20 and the stator 30 have the above-described configuration. Therefore, as shown in FIG. 8, the waveform of the cogging torque generated between the first magnet 23 and the first stator core 31 is different from the waveform of the cogging torque generated between the second magnet 24 and the second stator core 32. On the other hand, the phases are reversed. The cogging torque of the motor 10 is the sum of these cogging torques. Thereby, the cogging torque of the motor 10 can be reduced. As a result, vibration, noise, and the like generated in the motor 10 can be reduced. Further, in the motor 10 of the present embodiment, the torque ripple can be reduced as compared with the conventional motor 10.

  According to this embodiment, the first magnet 23 and the second magnet 24 of the rotor 20 have the same magnetic flux density and different shapes. Thus, by making the shapes of the first magnet 23 and the second magnet 24 different from each other, the phase of the cogging torque generated between the first magnet 23 and the first umbrella 35 and the second The phase of the cogging torque generated between the magnet 24 and the second umbrella 36 can be shifted from each other. Thereby, the cogging torque generated between the first magnet 23 and the first umbrella 35 and the cogging torque generated between the second magnet 24 and the second umbrella 36 cancel each other, The combined cogging torque in the motor 10 including the rotor 20 can be reduced. As a result, the rotor 20, the motor 10, and the electric power steering device 500 described later can suppress vibration and noise generated during operation. By employing such a configuration, there is no need to skew the first magnet 23 and the second magnet 24, and as a result, the assembly process can be simplified.

According to the present embodiment, the first magnet 23 and the second magnet 24 have the same volume. The dimensions of the first magnet 23 and the second magnet 24 are different from each other in at least one of a circumferential direction, a central axis J direction, and a radial direction about the central axis J. The position of the center Mc in the circumferential direction is the same between the first magnet 23 and the second magnet 24. Further, the first magnet 23 and the second magnet 24 have different cross-sectional areas in a cross section orthogonal to the axial direction. Further, the first magnet 23 and the second magnet 24 are made of the same type of magnetic material.
Thus, the cogging torque can be easily suppressed without skewing the first magnet 23 and the second magnet 24.

  According to the present embodiment, the first outer surface portion 23t of the first magnet 23 and the second outer surface portion 24t of the second magnet 24 are such that the outer peripheral surface facing outward in the radial direction is centered on the central axis J. It has an arc shape and the same radius of curvature. Thereby, the air gap between the rotor 20 and the stator 30 can be made uniform. As a result, the cogging torque can be suppressed, and the flow of the magnetic flux becomes smooth, so that the torque can be increased.

  According to this embodiment, the first umbrella 35 and the second umbrella 36 of the stator 30 have different widths in the circumferential direction. By making the shapes of the first umbrella 35 and the second umbrella 36 different from each other, the cogging torque generated between the first magnet 23 and the first umbrella 35 and the second magnet The phase can be shifted from each other by the cogging torque generated between the second umbrella 24 and the second umbrella 36. Thereby, the cogging torque generated between the first magnet 23 and the first umbrella 35 and the cogging torque generated between the second magnet 24 and the second umbrella 36 cancel each other, The combined cogging torque in the motor 10 including the stator 30 can be reduced. As a result, vibration and noise generated in the motor 10 can be suppressed. By employing such a configuration, it is not necessary to change the position of the teeth in the circumferential direction along the axial direction, and as a result, the winding process can be simplified.

  According to the present embodiment, the dimensions of the first umbrella 35 and the second umbrella 36 are different from each other in at least one of the circumferential direction and the axial direction. Thereby, the phase of the cogging torque generated between the first magnet 23 and the first umbrella 35 and the phase of the cogging torque generated between the second magnet 24 and the second umbrella 36 become mutually different. Can be shifted.

  According to the present embodiment, the first teeth 33 and the second teeth 34 are arranged at the same position in the circumferential direction, and have the same width dimension in the circumferential direction. Accordingly, the phases of the cogging torques generated between the first magnet 23 and the first umbrella 35 and between the second magnet 24 and the second umbrella 36 are more easily shifted. Thereby, the combined cogging torque in the motor 10 can be reduced. As a result, vibration and noise generated in the motor 10 can be suppressed. Further, since the first teeth 33 and the second teeth 34 have the same shape of the portion around which the conductive wire forming the coil 30C is wound, the width dimension of the first umbrella 35 and the second umbrella 36 is smaller. Even if they are different from each other, it is possible to easily form the coil 30 </ b> C by winding a conductive wire around the first teeth 33 and the second teeth 34.

  According to the present embodiment, the first umbrella 35 and the second umbrella 36 are formed such that the axial lengths L11 and L12 are the lengths of the first magnet 23 and the second magnet 24 that are radially opposed to each other. It is the same as L1 and L2. Thereby, the shape of the portion around which the conductive wire forming coil 30 </ b> C is wound is the same in first teeth 33 and second teeth 34. For this reason, even if the shape of the umbrella is different, the coil can be easily wound to form the coil 30C.

[Electric power steering device]
FIG. 9 schematically illustrates an electric power steering device 500 including the motor 10 according to the present embodiment.
As shown in FIG. 9, the electric power steering device 500 is provided in a vehicle such as an automobile. The electric power steering device 500 includes a steering system 520 and an auxiliary torque mechanism 540.

  The steering system 520 is, for example, a steering handle 521, a steering shaft 522 (also referred to as a “steering column”), a universal joint 523A, 523B, and a rotating shaft 524 (also referred to as a “pinion shaft” or an “input shaft”). ), A rack and pinion mechanism 525, a rack shaft 526, left and right ball joints 552A and 552B, tie rods 527A and 527B, knuckles 528A and 528B, and left and right steering wheels (for example, left and right front wheels) 529A and 529B.

  The steering handle 521 is connected to a rotating shaft 524 via a steering shaft 522 and universal shaft joints 523A and 523B. The rotation shaft 524 is connected to a rack shaft 526 via a rack and pinion mechanism 525. The rack and pinion mechanism 525 includes a pinion 531 provided on the rotation shaft 524, and a rack 532 provided on the rack shaft 526. The right end of the rack shaft 526 is connected to the right steering wheel 529A via a ball joint 552A, a tie rod 527A, and a knuckle 528A. The left end of the rack shaft 526 is connected to the left steering wheel 529B via a ball joint 552B, a tie rod 527B, and a knuckle 528B. Here, the right side and the left side respectively correspond to the right side and the left side viewed from the driver sitting on the seat.

  The steering system 520 generates a steering torque when the driver operates the steering handle 521. The steering torque is transmitted to left and right steering wheels 529A and 529B via a rack and pinion mechanism 525. Thus, the driver can operate the left and right steering wheels 529A, 529B.

  The auxiliary torque mechanism 540 includes, for example, a steering torque sensor 541, an ECU 542, a motor 543, a speed reduction mechanism 544, and a power converter 545. The auxiliary torque mechanism 540 applies an auxiliary torque to a steering system 520 from the steering handle 521 to the left and right steering wheels 529A, 529B. Note that the auxiliary torque may be referred to as “additional torque”.

  The motor 543 corresponds to the motor 10 in the present embodiment.

  The steering torque sensor 541 detects the steering torque of the steering system 520 given by the steering handle 521. The ECU 542 generates a drive signal for driving the motor 543 based on a detection signal (hereinafter, referred to as “torque signal”) from the steering torque sensor 541. The motor 543 generates an auxiliary torque corresponding to the steering torque based on the drive signal. The assist torque is transmitted to the rotation shaft 524 of the steering system 520 via the speed reduction mechanism 544. The reduction mechanism 544 is, for example, a worm gear mechanism. The auxiliary torque is further transmitted from the rotation shaft 524 to the rack and pinion mechanism 525.

  The electric power steering device 500 can be classified into a pinion assist type, a rack assist type, a column assist type, and the like, depending on the location where the assist torque is applied to the steering system 520. FIG. 9 illustrates a pinion assist type electric power steering device 500. However, the electric power steering device 500 may be a rack assist type, a column assist type, or the like.

The ECU 542 may receive not only a torque signal but also a vehicle speed signal, for example. The external device 560 is, for example, a vehicle speed sensor. Alternatively, the external device 560 may be another ECU that can communicate with an in-vehicle network, such as a CAN (Controller Area Network). The microcontroller of the ECU 542 can perform vector control or PWM control of the motor 543 based on a torque signal, a vehicle speed signal, and the like.
The electric power steering device 500 operates the left and right steering wheels 529A and 529B by using a composite torque obtained by adding the assist torque of the motor 543 to the steering torque of the driver.

(Modification of stator)
FIG. 10 is a partial perspective view of a stator 130 of a modified example that can be adopted in the above-described embodiment. In this modification, the configuration other than the stator 130 is the same as that of the above-described embodiment. That is, the stator 130 is radially opposed to the rotor 20 (see FIG. 4) of the above-described embodiment.

  As shown in FIG. 10, the stator 130 of the present modification has an umbrella 135 that radially opposes the first magnet 23 and the second magnet 24 shown in FIG. The umbrella 135 extends in the axial direction with a uniform width.

  Even if the width of the umbrella 135 is uniform in the axial direction as shown in the present modification, the use of the rotor 20 shown in the above-described embodiment allows the first magnet 23 and the umbrella 135 to be separated from each other. The phases of the generated cogging torque and the cogging torque generated between the second magnet 24 and the umbrella 135 can be shifted from each other. Thereby, the combined cogging torque in the motor 10 including the rotor 20 can be reduced.

(Modified example of rotor)
FIG. 11 shows a rotor 220 according to a modified example of the above-described embodiment. In this modification, the configuration other than the rotor 220 is the same as that of the above-described embodiment. That is, the rotor 220 is radially opposed to the stator 30 (see FIG. 7) of the above-described embodiment.

  As shown in FIG. 11, the rotor 220 of the present modification has a magnet 123 radially opposed to the first umbrella 35 and the second umbrella 36. The magnet 123 extends in the axial direction with a uniform width.

  Even if the width dimension of the magnet 123 is uniform along the axial direction as shown in this modification, by using the stator 30 shown in the above-described embodiment, the gap between the magnet 123 and the first umbrella 35 can be reduced. The phase of the generated cogging torque and the phase of the cogging torque generated between the magnet 123 and the second umbrella 36 can be shifted from each other. Thereby, the combined cogging torque in the motor 10 including the stator 30 can be reduced.

  As described above, one embodiment of the present invention and its modified example have been described. However, each configuration in the embodiment and the modified example and a combination thereof are examples, and addition of the configuration may be performed without departing from the gist of the present invention. , Omissions, substitutions and other changes are possible. The present invention is not limited by the embodiments.

  For example, the first stator core 31 and the second stator core 32 may have different lengths L1 and L2 in the axial direction. That is, in the axial direction, the length L1 of the first core back portion 37 may be different from the length L2 of the second core back portion 38. Further, the axial length L11 of the first umbrella 35 may be different from the axial length L12 of the second umbrella 36.

  Further, the first magnet 23 and the second magnet 24 may be made of different types of magnetic materials. With such a configuration, even if the first magnet 23 and the second magnet 24 are made of different kinds of magnetic materials, the shapes of the first magnet 23 and the second magnet 24 are different. Are different from each other, the cogging torque can be set to the opposite phase. Thereby, the cogging torque generated between the first magnet 23 and the first umbrella 35 and the cogging torque generated between the second magnet 24 and the second umbrella 36 cancel each other, The combined cogging torque in the motor 10 including the stator 30 can be reduced. As a result, vibration and noise generated in the motor 10 can be suppressed.

In the above-described embodiment, the rotor 20 having the two magnets (the first magnet 23 and the second magnet 24) having different shapes and arranged in the axial direction has been described. However, the rotor may have three or more magnets arranged in the axial direction. In this case, among the three or more magnets arranged in the axial direction, at least two magnets may have different shapes.
Similarly, in the above-described embodiment, the stator 30 having two umbrellas (a first umbrella 35 and a second umbrella 36) having different widths in the circumferential direction and arranged in the axial direction has been described. However, the stator may have three or more umbrellas arranged in the axial direction. In this case, it is sufficient that at least two of the three or more umbrellas arranged in the axial direction have different width dimensions.

  The motor 10 of the above-described embodiment and its modified example is widely used not only for the electric power steering device 500 but also for various devices including various motors such as a vacuum cleaner, a dryer, a ceiling fan, a washing machine, and a refrigerator. Can be done.

  2, CL, 10, 543, motor, 20, 220, rotor, 21, shaft, 22, rotor core, 23, first magnet, 23t, first outer surface (outer peripheral surface), 24, second magnet, 24t ... second outer surface portion (outer peripheral surface), 30, 130 ... stator, 30C ... coil, 31 ... first stator core, 32 ... second stator core, 33 ... first teeth, 34 ... second teeth, 35 ... first Umbrella, 36 ... second umbrella, 37 ... first core back portion, 38 ... second core back portion, 123 ... magnet, 135 ... umbrella, 500 ... electric power steering device

Claims (13)

A shaft that rotates about a central axis extending along the vertical direction,
A rotor core fixed to the shaft,
A plurality of first magnets provided in a part of the rotor core in the axial direction and arranged at intervals in the circumferential direction;
A plurality of second magnets provided at a position different from the first magnet in the axial direction of the rotor core and arranged at intervals in the circumferential direction;
With
The rotor, wherein the first magnet and the second magnet have the same magnetic flux density and different shapes. The first magnet and the second magnet have the same volume,
The rotor according to claim 1.   3. The rotor according to claim 1, wherein the first magnet and the second magnet have different dimensions in at least one of a circumferential direction, an axial direction, and a radial direction. 4.   The rotor according to any one of claims 1 to 3, wherein the first magnet and the second magnet have the same center position in the circumferential direction. The rotor according to any one of claims 1 to 4, wherein the first magnet and the second magnet have different cross-sectional areas in a cross section orthogonal to the axial direction.   The rotor according to any one of claims 1 to 5, wherein the first magnet and the second magnet are made of the same type of magnetic material.   The rotor according to any one of claims 1 to 6, wherein the first magnet and the second magnet are made of different types of magnetic materials.   The first magnet and the second magnet, wherein an outer peripheral surface facing radially outward has an arc shape centered on the center axis, and has the same radius of curvature as each other. A rotor according to claim 1. A rotor according to any one of claims 1 to 8,
A stator radially opposed to the rotor via a gap,
A motor. The stator is provided at a plurality of first teeth arranged at intervals in a circumferential direction, and at a radially inner end of the first teeth, and is provided at a radially opposite end of the first magnet. One umbrella and
A plurality of second teeth arranged at intervals in a circumferential direction, and a second umbrella provided at a radially inner end of the second teeth and radially facing the second magnet. ,
The motor according to claim 9, wherein the first umbrella and the second umbrella have different widths in a circumferential direction.   The motor according to claim 10, wherein the first teeth and the second teeth are arranged at positions where centers of widths in a circumferential direction overlap with each other in an axial direction, and have the same width in the circumferential direction.   The said 1st umbrella and the said 2nd umbrella, The axial length is the same as the said 1st magnet and the said 2nd magnet which are diametrically opposed, The Claims 10 or 11 characterized by the above-mentioned. motor.   An electric power steering device comprising the motor according to any one of claims 9 to 12.

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